DESCRIPTION: The long term goal of this project is to construct engineered libraries of functional polyketide synthases (PKSs) in yeast. The large numbers of novel polyketide molecules generated by this approach will be isolated and screened for their biological activities in a number of commercially relevant assay systems. In addition, the libraries will be configured for screening in yeast cell-based assay systems in which biologically active molecules will be identified through their ability to stimulate yeast growth in an autocrine manner. Phase I of this project will be focused on the demonstration of the feasibility of expression of PKSs and subsequent production of polyketides in yeast. PKSs from two types of PKS gene clusters will be engineered for expression in Saccharomyces cerevisiae. From the iterative or aromatic class of PKS, we will express the single polypeptide chain involved in the biosynthesis of 6-methylsalicylic acid (6-MSAS), and the 3 polypeptides encompassing the minimal PKS of actinorhodin. We will also express loading domains and modules derived from the spiramycin and erythromycin gene clusters. PROPOSED COMMERCIAL APPLICATION: NOT AVAILABLE